The role of hydrogen in heavily doped amorphous silicon

Abstract

Amorphous silicon films have been grown in a d.c. glow discharge in silane (SiH₄) containing 1–4 vol.% of either diborane (B₂H₆) or phosphine (PH₃). Deposition parameters such as substrate temperature, flow rate, pressure and power were varied, and properties such as composition, conductivity, optical absorption and infrared absorption were studied. Compositional profiles were obtained with secondary ion mass spectroscopy and show that both the hydrogen and dopant concentrations are influenced by the deposition conditions. The experimental results indicate that hydrogen plays a dominant role in determining the conductivity of these heavily doped amorphous silicon films.